Car won’t make over 20psi on e85?

[forcefed86]

Setup in Sig is current. The same setup last year made 30+psi with no issues. The only change is the switch to e85, 83lb injectors and new turbo tweak chip, magnaflow 750 fuel pump with ½” lines, old 204/214 cam to new 218/218. Using 100# springs and compression up from stock to roughly 9:1. Custom push rod length for proper preload.

I’m running the same times as last year on 19psi and 16*timing. Last year I was on meth injection and pump gas 30psi and 23* timing. 10.7x’s around 128-130.

I dropped my plug gap to .020 before going ot the track. I have since dropped the gap to .018. My setup is a bit odd with fueling and timing. Any leaner than high 10.7 or so and I’ll knock. Any less timing than 14* and I’ll knock. And more timing than 18* and I’ll knock.

I’m confused… This thing runs great but it’s totally opposite of the usual e85 buick.

Any ideas folks?

 

[TurboBuRick]

Post a log.

 

[forcefed86]

Don't have A logger...

 

[forcefed86]

I was told by the NGK tech department that running a non-resister plug (nkg 4554's, -9's) can cause a large amount of RF interference with a stock ignition system/ fuel injection wiring harness/stock computer etc.

Anyone have any experiance with this?

 

[GNVYUS 1]

This is a bit confusing

1) Run the resistor, it's the Projected Tip aspect of the spark plug that you want to ditch when running really High Psi to lessen pre-ignition and detonation.

2) Running a lesser gap isn't going to lessen detonation, it's only going to help spark blow out which on GN's isn't like our DSM's. My GN running .035 at 25psi so that's not going to lessen your detonation. It's possible your plug is too hot and the projector tip isn't helping here.

I've followed your headgasket failure and somethings really out of whack here, not sure why your new engine is running less boost and timing than with pump and alky.

Have you ever confirmed the static compression #? Almost sounds like a 10:1 + engine with how little psi and timing it likes before detonating on you.

What's your IDC at WOT and ever had your injectors flowed?
This all could be one cylinder acting up due to an injector or arcing injector harness wire etc.

 

[forcefed86]

Erics Chips do not allow u to see timing or Idc on the. SM2. My Inj. were flowed. Running non-projected. Ngk. 9 heat range. My cranking comp is only 155ish. I've done all the math should be right around 9:1. Factory. Deck and bore. 41cc head. .033 HG. 24.48cc dished piston. I'm out of ideas... since I dont seem to be. Detonating, I thought I might be blowing out spark. That is why I tightened up the gap.

 

[forcefed86]

Sorry about the above post, tried to reply with my phone. I'm also wondering if valve spring pressure is coming into play. Since I did change the cam maybe the springs aren't heavy enough at high boost? I'll have to look into it abit more. I believe the webber uses 100# springs. I'll have to verify this. I have heard people having issues 90lb springs floating and went to 110# with the 218/218 flat tappet.

Thanks all!

 

[413turbo]

sure fuel pressure is rising w/ boost?

 

[GNVYUS 1]

Ok so you've got some solid info, I'd find out as much about the timing as possible and here is something to try.

That NGK plug (5671A-9 correct) appears to be 2 ranges colder than stock, but I can't seem to find it in the Sparkplugs.com chart? Most on here running high 20's are running the UR5, I'm going to go with the YR5 since it's a non projected tip plug. FWIW NGK doesn't seem to make a YR6 which I'd consider for near 30psi and beyond. I'd start here and see if $15 can clear up your issue gapped at .032.

Here is what the Supra guys are saying about the NGK 5671A-9, even they say they're too cold and one had them foul out every month. What's odd is since when do we run similar plugs as the Supra's?
NGK plugs with a 9 heat range?

Here is a good link to the plug I mentioned and at the top you can tweak the settings and find other plugs.
Sparkplugs.com - Search by Characteristic

When you say can't make over 20psi, you mean because of knock correct?
If not, valve springs can be a culprit and the usual suspect here. But a floating valve will hurt rpm and power, haven't heard of it inducing knock.

After seeing how the last engine blew the headgasket at low boost, I think we can rule out false knock and things like the lifters setting it off.

I guess it can't hurt to do a visual check on all of your injector harness wires but this issue is really hidden somewhere.

 

[forcefed86]

Appreciate the help!

This is defiantly an RPM/Power issue, not detonating that I can tell as long as the timing is low and the AFR is rich as stated. Sorry, I see I didn't make that very clear.

I've been reading up on some of the boosted SBC guys experiences. Some of them run gaps down in the .017 range on single coil setups. With the rain I haven't had a chance to try the car at .018 gap yet. Also planning to take off a spring and verify it’s open/closed pressure. I couldn’t spin and springs by hand so I’m guessing they aren’t crazy loose at least. I would think if it was springs, it would be more RPM related and not so much boost? The car is an animal at 20psi and runs nice and clean down the track to 6100 or so. Put the boost up to 23 or so and is noticeable ruff running and performs poorly.(feels like IGN breakup/spark blow-out) It will continue to raise RPM but runs poorly. (no retard or audible alarm from sensor)


To make things worse, I’m actually using the R5674-10 (6702) Racing Spark Plug. The plugs aren’t fouling out. The methanol guys at the track told me they always went with the coldest plug possible without fouling on alcohol engines. Do you think to cold of a plug will cause spark to blow out? These were new plugs with maybe 15 miles on them and 6 track passes. The way it as explained to me there is no reason to have a hot plug in an alcohol engine. Thanks for the suggestion I will try a warmer plug for sure.(I’ll try anything at this point!)

THe yr5 looks pretty hot? Heat range 6 is OEM correct?

Looks like we could run a 5657 (8 heat range non proj)
5034 (7 ... )

The thing I'm wondering about is the non-resistor part all the NGK plugs run. Not sure if the AC delco plugs have a resistor or not.

Thanks!

Oh and here is a good NGK chart.

http://www.ngksparkplugs.com/images/pdfs/product_list.pdf

 

[GNVYUS 1]

Ok that makes more sense, boost increase is difficult, the valve springs are a great 1st option. Check for valve pressures and see if the 100-110's will help.

That chart was better, reaches are different which makes more sense now between those plug #'s with the Supra I posted.

Damn, the YR5 was supposed to be a Resistor plug with a non projected tip, your chart doesn't show that. Between Delco and NGK I'm shooting blanks here.

Also, does it seem like that NGK chart is saying the plugs you've been running are even COLDER than the UR6 plug?
If this is true, than you're sticking an icicle in there.

Personally on street cars with boost, running a super cold plug is pointless unless your a Supra running 40+psi occasionally and don't mind swapping plugs every oil change. That's why just ditching the projector tip and keeping the plug 1 range colder would make more sense here. Better idle and cruise combustion with help at 25psi + from the non projected tip.

Anyways, your gaps are so tight that I wonder if your coilpack is super weak. I'll ditch mine when it hits 50k or when it starts missing up top on gaps it used to fire on. I've been firing the E3 (pregapped to .040) at 25psi and during my initial FMICless test it got to 30psi and my coilpack is probably 10k miles old.

Might want to save up for Bob Baileys COP, that will fire off a rocket in there.

 

[forcefed86]

Ok that makes more sense, boost increase is difficult, the valve springs are a great 1st option. Check for valve pressures and see if the 100-110's will help.

That chart was better, reaches are different which makes more sense now between those plug #'s with the Supra I posted.

Damn, the YR5 was supposed to be a Resistor plug with a non projected tip, your chart doesn't show that. Between Delco and NGK I'm shooting blanks here.

Also, does it seem like that NGK chart is saying the plugs you've been running are even COLDER than the UR6 plug?
If this is true, than you're sticking an icicle in there.

Personally on street cars with boost, running a super cold plug is pointless unless your a Supra running 40+psi occasionally and don't mind swapping plugs every oil change. That's why just ditching the projector tip and keeping the plug 1 range colder would make more sense here. Better idle and cruise combustion with help at 25psi + from the non projected tip.

Anyways, your gaps are so tight that I wonder if your coilpack is super weak. I'll ditch mine when it hits 50k or when it starts missing up top on gaps it used to fire on. I've been firing the E3 (pregapped to .040) at 25psi and during my initial FMICless test it got to 30psi and my coilpack is probably 10k miles old.

Might want to save up for Bob Baileys COP, that will fire off a rocket in there.

Funny you mention the coil pack. I just put my old RT42TS plugs gapped at 30 and went on a test run. Idle was better, cruise was great. The car wouldn't even make a 1lb of boost without breaking up. I think my coil pack may be to blame I didn't change anything else. I do have a spare somewhere. I'll swap it in and see if it improves. I have to say between the module and coil packs I've had nothing but bad luck with these cars. The coil pack is less than a year old and an ACdelco. Module is a magnavox unit also less than a year old. All parts not even 500 miles.

Suppose I shouldn't complain if it is something that easy. Wasn't there a coil special going on with one of the vendors? I think caspers made a high output coil for our cars too right?

 

[forcefed86]

Just ordered high output coil pack... couldn't find my spare. Very reasonable price as well.

Coil Pack - High Output

 

[GNVYUS 1]

He's the guy, hard to believe they're $40 after all these years. :biggrin: Good for us.

Ah, that's definitely pointing towards an ignition issue now, these coil packs and those lame male connectors UNDER the hot coil pack and in between another electronic device wasn't the smartest move. They got a lot right back in 1984-85 when redesigning the Hot Air but that coil pack connection isn't one.

Did you ever notice a huge lose in MPG and warm up temps opening the thermo quicker in the new engine? I'd bet your weak coil pack with those super cold plugs and tight gap were leaving some unburnt fuel in the cylinder and causing the engine to warm up quicker than usual.

Also, we can probably start a thread on plugs but, the NGK you were running 5674-10, is a non resistor but has the projected tip.
I think this plug might be the NGK I've been talking about.
NGK Spark Plugs 2817 - NGK Racing Spark Plugs - Overview - SummitRacing.com
NGK 5673-7 or # 2817. Appears to be 1 range colder, non resistor (no choice here) and non projected tip. That should have a normalish combustion while idling and cruising, be just cold enough at high boost and with the non projector tip help with any pre-ignition or detonation at 25psi +.
That's my guy.

Anyways, post back when you get the new coil pack and it's probably best to leave those AC plugs in it to compare. Hopefully that's all you'll need to be boosting again.

 

[forcefed86]

I feel bad I have quite a bit of misinformation and this site won't let me go back and modify my old posts. I originally ordered the incorrect 3/4" reach (gasket type) NGK plugs Heat range 10 plug. (I think these are the plugs the supras use, and the buick guys with aftermarket heads)

After confirming last night I was running the R5673-9 (3442). This is a non-projected style and the proper tapered seal type plug for our OEM heads. It is 5 steps colder than stock.

The autolite AR-135 is also a nickel plated recessed plug that looks comparable to the 2817 NGK. They also have the cut back ground electorde.

This is a great chart, resolution is poor but readable!

 

[GNVYUS 1]

LOL, we should start a new thread on plugs, we're both spewing out plug #"s like crazy. But the R5673-9 (5 steps colder) isn't a plug for a GN under 30psi that spends the majority of it's life on the street, IMO. I'm not sure who'd qualify for that plug around here.

I can barely make out the numbers but what I thought the NGK chart was showing concerning plug coldness was correct, the 5673-7 is COLDER than the UR6. Your new chart shows it as 3 steps colder (implying from stock) so even THAT plug I mentioned is too cold for the majority of us.

I guess my initial plug, the YR5 (not in chart?), works as the non projected tip and 1 heat range colder for us. If you use the tip designation part and zip down you'll see the first non projected is the R5673-6 and that says 2 heat ranges down, that's really as cold as I'd go for us since we're all living under 30psi most of the time.

At least we have an idea of what NGK plugs are more practical for us to run after all this.

 

[forcefed86]

Back to the topic....

Swapped out an old coil I found in the attic and there was no real change. The local Orileys did have an AR-135 plug. I tried swapping in these plugs and at the same time I installed an old set of 9mm "race" wires. I was running new autozone specials (still and 8mm wire and cheap worked great last season). These plugs have the ground strap cut back so I it would be awkward gapping them. Best I could tell these are pre-gapped at around .020-.022? Using a wafer style gapper and it isn't long enough to get an accurate reading. Anyway I'm able to boost again... and hit 25psi at 18* timing with no knock at 10.9 AFR.

I'll swap back my cheap wires and see if that was the issue. Hope to get kicked out of the track tonight for going faster than my roll bar is rated! 25psi feels goood!

 

[GNVYUS 1]

That's way better news, cheap fix. Gap is still low but you can always test it out little by little if the plugs are a pain to regap.